KR101807165B1

KR101807165B1 - Bolt coating composition and the coating method of bolt

Info

Publication number: KR101807165B1
Application number: KR1020150180942A
Authority: KR
Inventors: 박종원; 이경황
Original assignee: 재단법인 포항산업과학연구원
Priority date: 2015-12-17
Filing date: 2015-12-17
Publication date: 2017-12-08
Also published as: KR20170072592A

Abstract

The composition for bolt coating according to an embodiment of the present invention includes a zinc-containing compound and a sol-gel compound having both an epoxy group and a silane group. The content of zinc particles in the sol-gel compound ranges from 60 wt% to 80 wt% .

Description

TECHNICAL FIELD [0001] The present invention relates to a bolt coating composition and a coating method of bolt,

The present invention relates to a composition for bolt coating and a coating method of the bolt using the same.

Commercialization of ternary alloy-plated steel sheet, which has improved corrosion resistance by 7 to 20 times compared to existing cold rolled steel sheets and zinc-coated steel sheets, has been actively conducted. The use of such high corrosion resistant alloy coated steel sheets is rapidly increasing in accordance with various demands of interior and exterior materials for construction, automobiles, home appliances and industry.

These high corrosion resistant steels are processed into various forms when they are applied to interior and exterior materials for construction, and they are fastened by bolts when forming structures. In the case of conventional cold rolled steel plate, it is fastened with chromate treatment bolt. In case of galvanized steel plate, electro-galvanized bolt with improved corrosion resistance is applied. In case of stainless steel plate, stainless steel bolt is used to complement the corrosion resistance of steel plate.

However, in the case of ternary alloy coated steel sheets, commercialization thereof has been relatively recent, and fastener parts suitable for the trivalent alloy coated steel sheet have not been developed. In the case of using an existing electroplated zinc plating bolt, the corrosion resistance is relatively low as compared with the steel plate, so that the corrosion progresses rapidly around the bolt, thereby severely reducing the durability of the entire structure. In addition, there is no problem of corrosion resistance when stainless steel bolt is applied, but it is inevitable that the overall price of the structure is increased because it is very expensive.

Therefore, it is required to manufacture a high corrosion resistance bolt that has corrosion resistance comparable to that of a ternary alloy-plated steel sheet which has a corrosion resistance seven times higher than that of a conventional galvanized steel sheet, and which can secure economical efficiency compared to a stainless steel bolt.

SUMMARY OF THE INVENTION The present invention provides a high corrosion resistance bolt coating composition and method of coating bolts.

In order to solve these problems, the composition for bolt coating according to an embodiment of the present invention may be a sol-gel compound having both an epoxy group and a silane group; And zinc particles, wherein the content of zinc particles relative to the sol-gel compound is from 60 wt% to 80 wt%.

The sol-gel compound having both the epoxy group and the silane group may be 3-glycidoxypropylmethyldiethoxysilane.

The zinc particles may include particles having a size between 4 탆 and 6 탆.

The zinc particles may include particles having a minor axis of 2 占 퐉 or less and a major axis of about 20 to 40 占 퐉.

The composition for bolt coating may further include acetone.

The composition for bolt coating may further comprise nitric acid.

A method of coating a bolt according to an embodiment of the present invention includes preparing a bolt coating composition, immersing a bolt in the bolt coating composition, and curing the immersed bolt, wherein the bolt coating A composition in a sol-gel state having both an epoxy group and a silane group; And zinc particles, wherein the content of zinc particles relative to the sol-gel compound is from 60 wt% to 80 wt%.

The step of immersing the bolt in the bolt coating composition may be performed at about 2800 rpm to about 3200 rpm using a spin coating apparatus.

Curing of the immersed bolts may be performed at a temperature of 200 to 220 degrees for 2 to 4 minutes.

The thickness of the coating film coated on the bolt by the coating method may be about 30 탆 to 50 탆.

The zinc particles may include particles having a size between 4 탆 and 6 탆.

The zinc particles may include particles having a minor axis of 2 占 퐉 or less and a major axis of about 20 占 퐉 to 40 占 퐉.

The composition for bolt coating may further include acetone.

The composition for bolt coating may further comprise nitric acid.

As described above, the coating composition and the coating method of the bolt according to an embodiment of the present invention have high internal corners, and thus the corrosion resistance of the bolt is remarkably improved when the bolt is coated with the coating composition.

1 is a cross-sectional view of a bolt coated with a coating composition according to an embodiment of the present invention.
2 is an enlarged view of a coating layer according to an embodiment of the present invention.
FIG. 3 is a graph showing the composition of the coating layer according to an embodiment of the present invention.
Figure 4 is an image showing the results of performing corrosion resistance tests on coated bolts and (central), conventional electroplated zinc plating bolts (right) according to one embodiment of the present invention.
FIG. 5 shows the result of performing repetitive fastening and corrosion resistance tests on coated bolts according to one embodiment of the present invention and a comparative example.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which: FIG. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

Now, a method of coating a bolt coating composition and a bolt according to an embodiment of the present invention will be described in detail.

First, a bolt coating composition according to an embodiment of the present invention will be described. The composition for bolt coating according to an embodiment of the present invention includes a zinc-containing compound and a sol-gel compound having both an epoxy group and a silane group. The content of zinc particles in the sol-gel compound ranges from 60 wt% to 80 wt% .

The coating composition for realizing a high corrosion resistance bolt should have excellent properties in terms of friction and abrasion considering high corrosion resistance and repetitive fastening. In addition, durability must be ensured while maintaining adhesion to the bolt base material.

For this purpose, the coating composition may be classified into a binder material and an additive. In the case of the binder, the coating composition is preferably composed of a material that improves adhesion with the base material and surface hardness, and the additive is preferably made of a material capable of securing corrosion resistance.

In the present embodiment, the sol-gel compound having an epoxy group and a silane group at the same time may be 3-glycidoxypropylmethyldiethoxysilane (GPTMS). The 3-glycidoxypropylmethyldiethoxysilane is used as a binder in the coating composition of this embodiment.

That is, the epoxy group of 3-glycidoxypropylmethyldiethoxysilane has the function of enhancing adhesion with the base material. Also, the Si-O-Si bond of the silane group of 3-glycidoxypropylmethyldiethoxysilane is excellent in surface hardness compared to the organic material, thereby improving the surface hardness of the coating.

In this embodiment, the zinc particle functions as an additive for improving the corrosion resistance. At this time, the zinc particles may simultaneously contain particles having a size of between 4 탆 and 6 탆, and particles having a minor axis of 2 탆 or less and a major axis of about 20 탆 to 40 탆. Since zinc particles of various sizes are included, the effect of improving the corrosion resistance is greater than when only one particle size is included.

Such a composition for bolt coating may further include acetone as a solvent. At this time, the content of acetone may be 1 to 3 times as much as the content of 3-glycidoxypropylmethyldiethoxysilane used as a binder.

The composition for bolt coating may further comprise nitric acid as a catalyst. At this time, the concentration of nitric acid contained may be about 0.1 N (normal concentration). The content of nitric acid may be in the range of 0.002 to 0.01 based on the content of 3-glycidoxypropylmethyldiethoxysilane.

The composition for bolt coating according to an embodiment of the present invention includes zinc particles in an amount of 60% by weight to 80% by weight. When the content of zinc particles is less than 60% by weight, the coating composition for bolt coating does not have sufficient corrosion resistance when coated with bolts. When the content of zinc particles is more than 80% by weight, .

Hereinafter, a method of coating a bolt according to an embodiment of the present invention will be described. A method of coating a bolt according to an embodiment of the present invention includes preparing a bolt coating composition, immersing a bolt in the bolt coating composition, and curing the immersed bolt, wherein the bolt coating Wherein the composition comprises a zinc compound and a sol-gel compound having both an epoxy group and a silane group, and the content of zinc particles in the sol-gel compound is 60 to 80 wt%.

First, the method will be described for preparing a composition for bolt coating. The composition for bolt coating prepared in this step is the same as the composition for bolt coating described above.

That is, the composition for the bolt coating may be 3-glycidoxypropylmethyldiethoxysilane (GPTMS), which is a sol-gel compound having both an epoxy group and a silane group. The zinc particles in the coating composition may simultaneously contain particles having a size of between 4 탆 and 6 탆 and particles having a minor axis of 2 탆 or less and a major axis of about 20 탆 to 40 탆. In addition, the composition for bolt coating may further include acetone as a solvent. At this time, the content of acetone may be 1 to 3 times the molar ratio of the content of 3-glycidoxypropylmethyldiethoxysilane used as the binder. Further, the composition for bolt coating may further comprise nitric acid as a catalyst. The concentration of nitric acid may be about 0.1 N (normal concentration). At this time, the content of 0.1 N nitric acid may be included in a molar ratio of 0.002 to 0.01 based on the content of 3-glycidoxypropylmethyldiethoxysilane.

In one embodiment of the invention, the coating composition comprises 0.5 to 1 mole of GPTMS, 1 to 1.5 moles of acetone, and 0.002 to 0.005 moles of 0.1 N nitric acid. Adding zinc particles having a size of 5 占 퐉 and zinc particles having a minor axis of 1 占 퐉 and a major axis of 30 占 퐉 in an amount of 70% by weight to the coating composition, followed by stirring at room temperature for 24 hours.

Next, the bolt is immersed in the composition for bolting coating. At this time, the immersion may be performed using a dip spin coater. The spin coating apparatus is a spin coating apparatus in which a coating composition is contained in a tank, the coating material is deposited into a tank to coat the coating material, and when the coating material is applied for a predetermined period of time, the coating material is taken out and rotated to form a coating solution It is a device to remove. The rotation rpm may be between about 2800 rpm and about 3200 rpm.

Next, the immersed bolts are cured. The coating composition on the surface of the bolt is cured without curing, so it is hardened and fixed to the bolt. The curing of the bolt may be performed at a temperature of 200 ° C to 220 ° C for 2 minutes to 4 minutes.

The thickness of the coating film coated on the bolt by the coating method may be between about 30 탆 and 50 탆. The thickness is a numerical range suitable for maintaining the bonding force between the bolt and the coupling object, without damaging it by friction or abrasion, while sufficiently improving the corrosion resistance of the bolt.

Hereinafter, the effect of improving the corrosion resistance of the coated bolt according to one embodiment of the present invention will be described.

1 is a cross-sectional view of a bolt coated with a coating composition according to an embodiment of the present invention. Referring to FIG. 1, it can be seen that the coating is uniform in thickness at the thread portion and the mountain portion of the bolt.

2 is an enlarged image of the coating layer. Referring to FIG. 2, it was confirmed that the zinc particles added as an additive in the coating layer of FIG. 2 were uniformly dispersed in the coating layer. That is, as shown in Fig. 2, zinc particles having a particle size of about 4 탆 to 6 탆 and particles having a minor axis of 2 탆 or less and a major axis of about 20 탆 to 40 탆 are homogeneously contained in the coating layer have.

Fig. 3 shows the composition of the coating layer analyzed. Referring to FIG. 3, it can be seen that the main components of the coating layer are composed of zinc (Zn) and silicon (Si).

Figure 4 is an image showing the results of performing corrosion resistance tests on coated bolts and (central), conventional electroplated zinc plating bolts (right) according to one embodiment of the present invention. The corrosion resistance test was carried out by spraying salt water on each bolt and observing the corrosion state after 840 hours.

As shown in FIG. 4, it was confirmed that rust appeared on the front surface of the zinc electroplating bolt (right side) according to the comparative example of the present invention. However, the coated bolts according to one embodiment of the present invention did not show any rust. Therefore, it was confirmed that the coating liquid composition according to an embodiment of the present invention and the coated bolt have improved corrosion resistance.

In addition, a bolt coated with a composition containing zinc as a general electrogalvanizing bolt and an epoxy-based solution, and a bolt coated with a solution impregnated with zinc particles in a 3-GPTMS binder as an embodiment of the present invention, a torque wrench 60N 占 퐉), the corrosion resistance was observed after repeated 40 times. For the corrosion resistance test, the brine was sprayed and the appearance was observed after 45 days. The results are shown in Fig.

As a result, the most corrosion was found in uncoated common electroplated zinc plated bolts. Next, corrosion was also observed in the bolts coated with the composition in which the epoxy-based solution was impregnated with zinc. However, almost no corrosion was observed in the bolts coated with the solution impregnated with zinc particles in the 3-GPTMS binder as in the embodiment of the present invention. Accordingly, it was confirmed that the coating liquid composition according to an embodiment of the present invention and the coated bolt have improved corrosion resistance and stability against repetitive fastening.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, Of the right.

Claims

A sol-gel-state compound having both an epoxy group and a silane group; And
Zinc particles,
The content of zinc particles in the sol-gel state compound is 60 wt% to 80 wt%
The zinc particles include two kinds of particles having different sizes,
Wherein the zinc particles comprise particles having a size of between 4 탆 and 6 탆, and particles having a minor axis of 2 탆 or less and a major axis of 20 탆 to 40 탆.

The method of claim 1,
Wherein the sol-gel compound having the epoxy group and the silane group simultaneously is 3-glycidoxypropylmethyldiethoxysilane.

delete

The method of claim 1,
Wherein the bolt coating composition further comprises acetone.

The method of claim 1,
Wherein the bolt coating composition further comprises nitric acid.

Preparing a composition for bolt coating;
Immersing the bolt in the bolt coating composition;
And curing the immersed bolt,
The composition for bolt coating is a sol-gel compound having both an epoxy group and a silane group; And zinc particles, wherein the content of zinc particles relative to the sol-gel compound is from 60% to 80% by weight,
The zinc particles include two kinds of particles having different sizes,
Wherein the zinc particles comprise particles having a size of between 4 탆 and 6 탆 and particles having a minor axis of 2 탆 or less and a major axis of 20 탆 to 40 탆.

8. The method of claim 7,
Wherein the step of immersing the bolt in the bolt coating composition is performed at 2800 rpm to 3200 rpm using a spin coating apparatus.

8. The method of claim 7,
Wherein the hardening of the immersed bolt is performed at a temperature of 200 to 220 degrees Celsius for 2 to 4 minutes.

8. The method of claim 7,
Wherein the thickness of the coating film coated on the bolt by the coating method is 30 占 퐉 to 50 占 퐉.

8. The method of claim 7,
Wherein the sol-gel compound having both the epoxy group and the silane group is 3-glycidoxypropylmethyldiethoxysilane.

delete

8. The method of claim 7,
Wherein the bolt coating composition further comprises acetone.

8. The method of claim 7,
Wherein the bolt coating composition further comprises nitric acid.